Posts tagged MRI
Articles and news from the latest research reports.
Blood May Hold Clues to Risk of Memory Problems After Menopause
New Mayo Clinic research suggests that blood may hold clues to whether post-menopausal women may be at an increased risk for areas of brain damage that can lead to memory problems and possibly increased risk of stroke. The study shows that blood’s tendency to clot may contribute to areas of brain damage called white matter hyperintensities. The findings are published in the Feb. 13 online issue of Neurology, the medical journal of the American Academy of Neurology.
The study involved 95 women with an average age of 53 who recently went through menopause. The women had magnetic resonance imaging, or MRIs, taken of their brains at the start of the study. They then received a placebo, oral hormone therapy or the hormone skin patch. They had MRIs periodically over the next four years.
During the study, women with higher levels of thrombogenic microvesicles, the platelets more likely to cause blood to clot, were likelier to have higher increases in the amount of white matter hyperintensities (shown as concentrated white areas on an MRI scan), which may lead to memory loss.
"This study suggests that the tendency of the blood to clot may contribute to a cascade of events leading to the development of brain damage in women who have recently gone through menopause," says study author Kejal Kantarci, M.D., of Mayo Clinic. "Preventing the platelets from developing these microvesicles could be a way to stop the progression of white matter hyperintensities in the brain."
All of the women had white matter hyperintensities at the start of the study. The amount increased by an average volume of 63 cubic millimeters at 18 months, 122 cubic millimeters at three years and 155 cubic millimeters at four years.
(Image: Shutterstock)
Subcortical Damage Is ‘Primary Cause’ of Neurological Deficits after ‘Awake Craniotomy’
Injury to the subcortical structures of the inner brain is a major contributor to worsening neurological abnormalities after “awake craniotomy” for brain tumors, reports a study in the February issue of Neurosurgery, official journal of the Congress of Neurological Surgeons. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.
During a procedure intended to protect critical functional areas in the outer brain (cortex), damage to subcortical areas—which may be detectable on MRI scans—is a major risk factor for persistent neurological deficits. “Our ability to identify and preserve cortical areas of function can still result in significant neurological decline postoperatively as a result of subcortical injury,” write Dr. Victoria T. Trinh and colleagues of The University of Texas MD Anderson Cancer Center, Houston.
Risk Factors for Neurological Deficits after Awake Craniotomy
The researchers analyzed factors associated with worsening neurological function after awake craniotomy for brain tumor surgery. In awake craniotomy, the patient is sedated but conscious so as to be able to communicate with the surgeon during the operation.
The patient is asked to perform visual and verbal tasks while specific areas of the cortex are stimulated, generating a functional map of the brain surface. This helps the surgeon navigate safely to the tumor without damaging the “eloquent cortex”—critical areas of the brain involved in language or movement.
The study included 241 patients who underwent awake craniotomy with functional brain mapping from 2005 through 2010. Of these, 40 patients developed new neurological abnormalities. Dr. Trinh and colleagues examined potential predictive factors—including changes on a type of MRI scan called diffusion-weighted imaging (DWI).
Of the 40 cases with new neurological deficits, 36 developed while the surgeon was operating in the subcortical areas of the brain. These are the inner structures of the brain, located beneath the outer, folded brain cortex. Just one abnormality developed while the surgeon was operating in the cortex only.
MRI Changes May Reflect Subcortical Damage
Neurological abnormalities developing while the surgeon was operating in the subcortex were likely to remain after surgery, and to persist at three months’ follow-up evaluation. Dr. Trinh and coauthors write, “Patients with intraoperative deficits during subcortical dissection were over six times more likely to have persistently worsened neurological function at three-month follow-up.”
In these patients, MRI scans showing more severe changes in the DWI pattern in the subcortex also predicted lasting neurological abnormalities. Of patients who had neurological deficits immediately after surgery and significant DWI changes, 69 percent had persistent deficits three months after surgery.
Patients who had “positive” cortical mapping—that is, in whom eloquent cortex was located during functional mapping—were somewhat more likely to have neurological abnormalities immediately after surgery. However, the risk of lasting abnormalities was not significantly higher compared to patients with negative cortical mapping.
Awake craniotomy with brain stimulation produces a “real-time functional map” of the brain surface that is invaluable to the neurosurgeon in deciding how best to approach the tumor. The new results suggest that, even when the eloquent cortex is not located on cortical mapping, subcortical areas near the tumor can still be injured during surgery. “Subcortical injury is the primary cause of neurological deficits following awake craniotomy procedures,” Dr. Trinh and colleagues write.
The researchers add, “Preserving subcortical areas during tumor resections may reduce the severity of both immediate and late neurological sequelae.” Based on their findings, they believe subcortical mapping techniques may play an important role in avoiding complications after awake craniotomy.
(Source: lww.com)
This Music Video Was Filmed Inside an MRI Machine
Musicians sometimes describe their music as an intimate look inside their minds. But an artist named Sivu has taken that notion literally with the music video for his song Better Man Than He that was actually filmed inside an MRI machine.
“Connection error” in the brains of anorexics
When people see pictures of bodies, a whole range of brain regions are active. This network is altered in women with anorexia nervosa. In a functional magnetic resonance imaging study, two regions that are important for the processing of body images were functionally more weakly connected in anorexic women than in healthy women. The stronger this “connection error” was, the more overweight the respondents considered themselves. “These alterations in the brain could explain why women with anorexia perceive themselves as fatter, even though they are objectively underweight” says Prof. Dr. Boris Suchan of the Institute of Cognitive Neuroscience at the Ruhr-Universität. Together with Prof. Dr. Dietrich Grönemeyer (University of Witten-Herdecke), Prof. Dr. Silja Vocks (University of Osnabrück) and other colleagues, the Bochum researchers report in the journal Behavioural Brain Research.
Anorexics misperceive their body shape
The researchers tested ten anorexic and fifteen healthy women of similar age. To start with, all the women judged on the computer which of several different silhouettes corresponded best to their own body shape. Ten control subjects who did not participate in the MRI scan answered the same question by matching a photo of the test subject to the right silhouette. Both healthy and anorexic women estimated their body shape differently than outsiders: healthy subjects rated themselves as thinner than the control subjects. Anorexic women on the other hand perceived themselves to be fatter than the control subjects did.
Brain areas for body perception examined with MRI
In MRI scanners, the researchers then recorded the brain activity of the 25 participants while they observed photos of bodies. Above all, they analysed the activity in the “fusiform body area” (FBA) and the “extrastriate body area” (EBA), because previous studies showed that these brain regions are critical for the perception of bodies. To this end, the neuroscientists from Bochum calculated the so-called effective connectivity between the FBA and EBA in both hemispheres. This is a measure of how much the activity in several brain areas is temporally correlated. A high degree of correlation is indicative of a strong connection.
Brains of anorexics structurally and functionally altered
The connection between the FBA and EBA was weaker in women with anorexia nervosa than in healthy women. In addition, the researchers found a negative correlation between the EBA-FBA connection in the left hemisphere and the misjudgement of body weight: the weaker the effective connectivity between the EBA and FBA was, the fatter the subjects with anorexia falsely estimated themselves to be. “In a previous study we found that there are structural changes in the brains of patients with anorexia”, says Boris Suchan. They have a lower density of nerve cells in the EBA. “The new data shows that the network for body processing is also functionally altered.” The EBA, which has a lower cell density in anorexics, is also the area that stood out in the connection analysis: it receives reduced input from the FBA. “These changes could provide a mechanism for the development of anorexia”, says Suchan.
The Science Behind ‘Beatboxing’
Acoustical analysis reveals the anatomy behind the fascinating array of sounds people can make.
Using the mouth, lips, tongue and voice to generate sounds that one might never expect to come from the human body is the specialty of the artists known as beatboxers. Now scientists have used scanners to peer into a beatboxer as he performed his craft to reveal the secrets of this mysterious art.
The human voice has long been used to generate percussion effects in many cultures, including North American scat singing, Celtic lilting and diddling, and Chinese kouji performances. In southern Indian classical music, konnakol is the percussive speech of the solkattu rhythmic form. In contemporary pop music, the relatively young vocal art form of beatboxing is an element of hip-hop culture.
Until now, the phonetics of these percussion effects were not examined in detail. For instance, it was unknown to what extent beatboxers produced sounds already used within human language.
To learn more about beatboxing, scientists analyzed a 27-year-old male performing in real-time using MRI. This gave researchers “an opportunity to study the sounds people produce in much greater detail than has previously been possible,” said Shrikanth Narayanan, a speech and audio engineer at the University of Southern California in Los Angeles. “The overarching goals of our work drive at larger questions related to the nature of sound production and mental processing in human communication, and a study like this is a small part of the larger puzzle.”
The investigators made 40 recordings each lasting 20-40 seconds long as the beatboxer produced all the effects in his repertoire, as individual sounds, composite beats, rapped lyrics, sung lyrics and freestyle combinations of these elements. He categorized 17 distinct percussion sounds into five instrumental classes — kick drums, rim shots, snare drums, hi-hats, and cymbals. The artist demonstrated his repertoire at several different tempos, ranging from slower at roughly 88 beats per minute, to faster at 104.
"We were astonished by the complex elegance of the vocal movements and the sounds being created in beatboxing, which in itself is an amazing artistic display," Narayanan said. "This incredible vocal instrument and its many capabilities continue to amaze us, from the intricate choreography of the ‘dance of the tongue’ to the complex aerodynamics that work together to create a rich tapestry of sounds that encode not only meaning but also a wide range of emotions."
"It is absolutely amazing that a person can make these sounds — that a person has such control over the timing of various parts of the speech apparatus," said phonetician Donna Erickson at the Showa University of Music and Sophia University, both in Japan, who did not participate in this study. "It is very exciting to see how far technology has come — that we can see these movements in real time. It gives us a much better understanding of how the various parts of our speech anatomy work."
GE Silent Scan turns down the volume on MRI scanners
GE Healthcare has introduced a new data acquisition technology designed to improve patient comfort by largely eliminating the horrible noise generated during an MRI scan. Conventional MRI scanners can generate noise levels in excess of 110 dBA (creating a din that sounds like a cross between a vehicle’s reverse warning horn and a Star Trek phaser) but GE says its new Silent Scan MRI technology can reduce this to just above background noise levels in the exam room.
The noise that MRI scanners produce is related to changes in the magnetic field that allow the slice by slice body scan to be carried out. In recent years, industry efforts to speed up the scanning process have also resulted in louder and louder scans. The designers have attempted to dampen these noises with mufflers and baffles, achieving only limited success.
Silent Scan is achieved through two new developments. First, acoustic noise is essentially eliminated by using a new 3D scanning and reconstruction technique called Silenz. When the Silenz protocol is used in combination with GE’s new high-fidelity MRI gradient and RF system electronics, the MRI scanning noise is largely eliminated at its source.
At the 2012 meeting of the Radiological Society of North America, an MRI system compatible with the Silent Scan technology was linked into a soundproof room. When the MRI system used conventional scanning methods, a staccato, stuttering racket with noise peaks up to 110 dBA was heard. However, when Silent Scan was switched on, the noise level dropped to 76 dBA, just above the background noise of the MRI electronics. This is accomplished without substantial trade-offs in scanning time or image quality, according to Richard Hausmann, president and CEO, GE Healthcare MR. The comparison is shown in this video.
Silent Scan technology has not yet obtained 510k Premarketing Notification clearance from the FDA, so it’s not yet available for sale. GE is presumably hoping for a decision that Silent Scan is “substantially equivalent” to existing MRI scanners, a result that would greatly simplify the new technology’s entry into the diagnostic market.
Your Brain on Big Bird: Sesame Street Helps to Reveal Patterns of Neural Development
Using brain scans of children and adults watching Sesame Street, cognitive scientists are learning how children’s brains change as they develop intellectual abilities like reading and math.
The novel use of brain imaging during everyday activities like watching TV, say the scientists, opens the door to studying other thought processes in naturalistic settings and may one day help to diagnose and treat learning disabilities.
Scientists are just beginning to use brain imaging to understand how humans process thought during real-life experiences. For example, researchers have compared scans of adults watching an entertaining movie to see if neural responses are similar across different individuals. “But this is the first study to use the method as a tool for understanding development,” says lead author Jessica Cantlon, an assistant professor in brain and cognitive sciences at the University of Rochester.
Eventually, that understanding may help pinpoint the cause when a child experiences difficulties mastering school work. “Psychologists have behavioral tests for trying to get the bottom of learning impairments, but these new imaging studies provide a totally independent source of information about children’s learning based on what’s happening in the brain,” says Cantlon.
The neuroimaging findings are detailed in a new study published Jan. 3 by the Public Library of Science’s open-access journal PLoS Biology, by Cantlon and her former research assistant Rosa Li, now a graduate student at Duke University.
Imaging Study Examines Effect of Fructose on Brain Regions That Regulate Appetite
In a study examining possible factors regarding the associations between fructose consumption and weight gain, brain magnetic resonance imaging of study participants indicated that ingestion of glucose but not fructose reduced cerebral blood flow and activity in brain regions that regulate appetite, and ingestion of glucose but not fructose produced increased ratings of satiety and fullness, according to a preliminary study published in the January 2 issue of JAMA.
“Increases in fructose consumption have paralleled the increasing prevalence of obesity, and high-fructose diets are thought to promote weight gain and insulin resistance. Fructose ingestion produces smaller increases in circulating satiety hormones compared with glucose ingestion, and central administration of fructose provokes feeding in rodents, whereas centrally administered glucose promotes satiety,” according to background information in the article. “Thus, fructose possibly increases food-seeking behavior and increases food intake.” How brain regions associated with fructose- and glucose-mediated changes in animal feeding behaviors translates to humans is not completely understood.
Kathleen A. Page, M.D., of Yale University School of Medicine, New Haven, Conn., and colleagues conducted a study to examine neurophysiological factors that might underlie associations between fructose consumption and weight gain. The study included 20 healthy adult volunteers who underwent two magnetic resonance imaging sessions in conjunction with fructose or glucose drink ingestion. The primary outcome measure for the study was the relative changes in hypothalamic (a region of the brain) regional cerebral blood flow (CBF) after glucose or fructose ingestion.
The researchers found that there was a significantly greater reduction in hypothalamic CBF after glucose vs. fructose ingestion. “Glucose but not fructose ingestion reduced the activation of the hypothalamus, insula, and striatum—brain regions that regulate appetite, motivation, and reward processing; glucose ingestion also increased functional connections between the hypothalamic-striatal network and increased satiety.”
“The disparate responses to fructose were associated with reduced systemic levels of the satiety-signaling hormone insulin and were not likely attributable to an inability of fructose to cross the blood-brain barrier into the hypothalamus or to a lack of hypothalamic expression of genes necessary for fructose metabolism.”
(Image: iStockphoto)
First motion MRI of unborn twins
If you want to get a sense of what it might be like to share a womb with a sibling, this video may give you a glimpse. For the first time, unborn twins have been captured using cinematic MRI, a technique that images slices of the body several times to create a video with astonishing detail.
According to Marisa Taylor-Clarke of Imperial College London, who recorded the images, this is “raw” footage, unlike typical videos of the womb, which require computer processing afterwards. She uses the technique to study twin-to-twin transfusion syndrome, a potentially fatal condition where one twin’s growth is stunted when its sibling receives more of the blood supply.
MRI Could Solve Cellphone Radiation Problems
Years of studies to determine whether cellphones can cause brain tumors have yielded one popular consensus: More studies are needed. One important piece that has been missing from researchers’ arsenals is a way to see what happens to cellphone radiation that is absorbed by the human brain. Two scientists have now developed a magnetic resonance imaging (MRI) technique that they say could solve that problem. This could be an important tool for researchers who are trying to discover whether extensive cellphone use can cause brain tumors or other health problems.
The technique creates high-resolution 3-D images of the heat created by cellphone radiation absorbed in the brain. In research reported this week in Proceedings of the National Academy of Sciences, the scientists demonstrate the method on cow brain matter and a gel that emulates brain tissue. But the procedure could easily be adapted for tests on human brains, says David Gultekin, a medical physicist at Memorial Sloan-Kettering Cancer Center, in New York, who led the development of the technique.